Electric discharge tube



2 Sheets-Sheet l Oct. 10, 1933. s. ZECHER ELECTRIC DISCHARGE TUBE Filed April 15. 1929 Oct. 10, 1933. G. ZECHER 1,930,070

ELECTRIC DISCHARGE TUBE I Filed April 15, 1929 2 Sheets-Sheet 2 Patented Oct. 10, 1933 UNITED STATES PATENT OFFICE ELECTRIC DISCHARGE TUBE Application April 15, 1929, Serial No. 355,333,

and in the Netherlands June 5, 1928 3 Claims.

The invention relates to electric discharge tubes, more particularly to those comprising an incandescent cathode and adapted to emit positive column light, and to devices comprising such a discharge tube.

With the constructions hitherto known of incandescent cathode electric discharge tubes with positive column-light the electrodes have always been secured to separate stems at both ends of the tube. In many cases this manner of taking out the electrodes entails difliculties, for example when a luminous tube has to be mounted in a reflector or when a tube destined for the emission of ultra-violet light has to be arranged in a substance which has to be irradiated.

According to the invention, in an electric discharge tube comprising an incandescent cathode and adapted to emit positive column-light, this difiiculty is obviated by leading out the electrodes at one end of the tube. In this case the .cathode may be arranged at the other end of the tube and, if the latter contains two anodes, a screen may be provided between them while the supply wires of the cathodes may be surrounded by insulating envelopes.

If the wall of the tube or at least part thereof is constituted by a material adapted to transmit ultra-violet rays, the said tube may be conveniently used for the irradiation of substances with ultra-violet light.

Preferably, the part of the tube near the points where the supply wires of the electrodes are taken out, is made wider than the other part of the tube. This construction permits an easier mounting of the tube in a device which may serve to irradiate susbtances with ultra-violet light. In -this case this widened portion of the tube may bear on a collar provided in the device.

The invention will be more clearly understood by referring to the accompanying drawings in which Fig. 1 represents a discharge tube with positive column-light according to the invention, which serves to radiate light, which tube is shown mounted in a reflector while Figs. 2 and 3 showing sections at right angles represent a device constructed in accordance with the invention and provided with parts by which the tube is adapted to irradiate substances with ultra-violet light.

Referring to Fig. 1, a discharge tube 1 comprises a stem 2, to which are secured a cathode 3, preferably an oxide-cathode and two anodes 4. Between the latter is arranged a screen 5 and the supply wires 6 of the cathode are surrounded by insulating envelopes '7. The upper end of the tube is surrounded by a cap 8 through which the current-supply wires of the cathode and the anodes are led out of the tube. The arrangement of the electrodes, i. e., cathode and anode on a single stem permits an easy mounting of the tube in a reflector 9 which for example has a parabolic section and which is closed at the top by a plate 10 which has an aperture destined for the passage of the luminous tube and on which bears the edge of the cap 20.

The device for irradiating substances with ultra-violet light as represented in Figs. 2 and 3, comprises a discharge tube 11 containing mercury vapour and, in addition,-preferably a rare gas, for example argon, and having a part 12 which ,consists of a substance adapted to transmit ultraviolet rays, for example of quartz. By means of several zones 13 which reckoned from the quartz part 12 have increasing coefiicients of expansion, the quartz part is connected with the part 14 which consists of a material in which the leading-in wires of the electrodes can be sealed.

Figures 2 and 3 show the tube as provided with a stem 15, supporting a cathode 16 at one end of the tube and anodes 17 at the opposite end thereof, a screen 20 being located between the two anodes. The wires 18 which supply the cathode with current are protected by envelopes of insulation material 19. The disposition of all the electrodes, i.e., cathode and anode, at one end of the tube, mounted on a single stem is of especial advantage for quartz, or other low expansion glass used for irradiation, for it requires only one graduated seal made up of the zones 13 between the material of the irradiating part of the tube and that of the stem part.

The upper part of the tube 14 has a larger diameter than the quartz part 12, so that the tube can be very easily arranged in a vessel 21 through which flows the substance to be irradiated, said substance being supplied and discharged at'22 and 23 respectively. Inside the vessel there is a collar 24 on which bears the widened portion of the discharge tube and which is pierced with apertures 25 which permit the substance being the passage of rays, but on the widened upper part 14 so that absorption of the ultra-violet rays by mercury condensed on the quartz portion 12 is avoided.

What I claim is:

1. In a positive column light tube, an elongated tube provided with an electrode stern member hermetically sealed into one end of the tube in combination with a pair of anodes and an intermediate cathode, the anodes being located adjacent the stem member and the cathode being located at the opposite end of the tube from the stem member, and at the ends of a pair of insulated lead wires extending the length of the positive column, both anodes and cathode being supported by said stem member.

2. In a positive column light tube, a tube member adapted to give off positive column light, and means for energizing said tube member comprising anode elements and an electron emitting cathode element, the lead wires of all of said elements being hermetically sealed through one end of the tube member, and said elements being spaced apart by a pair of insulated lead wires extending the length of the positive column to cause the positive light column to traverse substantially the full length of the tube member.

3. In a positive column light, a tube member, anodes spaced apart at one end of the tube, and a cathode at its other end at the ends of a pair of insulated lead wires extending the length of the positive column in combination with a shield element located between said anodes.

GUSTAV ZECHER. 

